418 C. CLIFFOED DOBELL. 



Sometimes excellent results may be obtained by making 

 ordinary dry films, fixing with absolute alcohol, and staining 

 in the usual way with (xiemsa or Leishman. This method is 

 not to be relied upon, however, and should never be employed 

 alone. Giemsa's new wet niethod (vide Giemsa, 1909, 1910) 

 appears to give excellent results, but I have not used it myselt" 

 for Bacteria. 



I have employed intra-vitam stains in many cases, but 

 with little success — so far as nuclear structures are concerned. 

 I have used neutral red, Brillantcresylblau, and methylene 

 blue. Many other workers appear to have been more 

 successful with these stains (e.g. Mencl, who has obtained 

 most striking results with polyclirome methylene blue). In 

 my experience, only non-living structures in the cells (meta- 

 chromatic granules, etc.) can be stained during life. But 

 doubtless much depends upon the stain itself. Different 

 samples of methylene blue — for example — may give quite 

 different cytological results. 



Descriptions of the Fokms Investigated. 



Having already given as briefly as possible the most im- 

 portant results which have been reached by previous work on 

 the cytology of Bacteria (see p. o99), I shall pass on to a detailed 

 description of my own observations. In this description I 

 shall make no attempt to compare or to correlate my own 

 results with those of others — my object being to give only the 

 facts which my own work has disclosed. A discussion of all 

 the results — obtained by other workers and by myself — will 

 be reserved for a subsequent section of the paper (see p. 

 462, et seq.). 



In describing the various forms which I have investigated, I 

 have — for convenience — divided the organisms into five main 

 groups. These are the Cocci, Bacilli, Spirilla, "fusiform 

 Bacteria," and a group of other organisms which resemble — 

 but are not — non-motile rod Bacteria. I shall deal with each 

 of these groups separately, and in this order. 



